Completely New Functionalities from Layered Superconductor/ferromagnet Nanostructures

Superconductivity and magnetism are usually thought to be mutually exclusive interacting states of electron systems. Nanofabrication techniques allow for a controlled combination of the two phenomena. In layered systems of ferromagnetic insulators and superconductors, the magnetism leaks into the superconductors, affecting their properties. Above all, we have shown that such "spin-split" superconductors coupled to electrodes via further magnetic contacts become strong thermoelectric devices, with an efficiency that can surpass that of all presently known thermoelectric materials. Because conventional superconductivity takes place only at low temperatures, this cannot be directly used for the usual application of thermoelectricity, i.e., converting waste heat into electrical power. However, I will tell how this effect can be used in constructing a completely new type of ultra-low-noise superconducting detector of electromagnetic radiation. In contrast to the existing device concepts, this thermoelectric detector (TED) does not require external bias power, which may allow for an easier scaling to a large number of detector pixels. In particular, I will describe the new FET Open project SUPERTED aimed at demonstrating such thermoelectric detection. If successful, this may become the detector of choice for future biomedical imaging measuring THz radiation emitted from the studied samples.